RESUMEN
This work was conducted to evaluate biological parameters of Plutella xylostella L. reared on leaves of several cauliflower genotypes under laboratory conditions. The experiment was set in a randomized block design and arranged in a 6 x 2 factorial (genotypes x generations). Leaf disks of the cultivars Barcelona, Verona, Piracicaba Precoce, Sharon, Silver Streak, and Teresópolis Gigante were placed in Petri dishes with 12 newly-hatched larvae. Leaf disks were initially changed after the fourth day, but daily afterwards until the larvae reached the pupal stage. The same procedure was adopted for the second generation. Twenty adults of each sex were separated from each genotype to evaluate their longevity, and 10 couples from each treatment were used to assess female fecundity. The lowest larval survival was obtained on the 'Silver Streak' (78.9 percent) and highest on 'Verona' (97.1 percent). The 'Silver Streak' and 'Teresópolis Gigante' showed the lowest pupal weights (4.83 mg and 5.11 mg, respectively), as well as the lowest fecundity, 119.4 and 123.0 eggs/female, respectively, while 'Piracicaba Precoce' the highest (167.7 eggs/female). Males obtained from larvae reared on 'Teresópolis Gigante' and 'Silver Streak' lived shorter (5.1 days), while the short-lived females were obtained from larvae reared on 'Barcelona' and 'Verona' (4.9 and 5.0 days). Insect development was prolonged in the second generation in all tested genotypes.
Asunto(s)
Animales , Brassica/genética , Brassica/parasitología , Lepidópteros/crecimiento & desarrollo , Genotipo , Larva , PupaRESUMEN
Avaliou-se a eficiência de Metarhizium anisopliae e Beauveria bassiana para o controle do pulgão Lipaphis erysimi (Kalt.) em couve Brassica oleracea L. var. acephala D.C., bem como sua compatibilidade com óleo de nim (Neemseto®). Dez isolados desses fungos foram utilizados, onde o isolado CG 001 de B. bassiana e o isolado CG 30 de M. anisopliae apresentaram-se como os mais virulentos com 90 por cento e 4,4 dias, e 64 por cento e 3,8 dias, de mortalidade e tempo letal médio, respectivamente. Bioensaios com o produto à base de nim nas concentrações 0,5; 1,0 e 2,0 por cento foram realizados por imersão foliar e pulverização sobre os pulgões. O tratamento com pulverização de 2,0 por cento de Neemseto® proporcionou mortalidade de 90 por cento. O teste in vitro de Neemseto® a 0,125; 0,25 e 0,5 por cento, sobre os isolados CG 001 de B. bassiana e CG 30 de M. anisopliae mostrou que esses isolados podem ter seu crescimento colonial e viabilidade alterados quando expostos a concentrações de nim maiores que 0,25 por cento. Em valores absolutos, os isolados CG 001 de B. bassiana e CG 30 de M. anisopliae foram os mais virulentos para L. erysimi, podendo ser utilizados no manejo dessa praga.
This work aimed to determine the efficiency of the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana to control the aphid Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae) in kale Brassica oleracea var acephala D.C., as well as their compatibility with a neem oil formulation (Neemseto®). Ten isolates of both fungi were tested and the most pathogenic ones were B. bassiana CG001 and M. anisopliae CG30 with 90 percent and 4.4 days, and 64 percent and 3.8 days of mortality and median lethal time, respectively. Bioassays with neem at concentrations of 0.5, 1.0 and 2.0 percent were done either by leaf discs dipping or spraying the aphids on the leaf discs. The neem spraying treatment at 2.0 percent provided 90 percent mortality. The use of B. bassiana isolate CG001 or M. anisopliae isolate CG30 with neem at 0.125, 0.25, and 0.5 percent, demonstrated that these isolates could have their spore viability or colony growth affected when exposed to neem concentrations higher than 0.25 percent. In absolute values, the isolates B. bassiana CG001 and M. anisopliae CG30 are the most virulent to L. erysimi, and could be utilized in the management of this pest.